This invention relates generally to demolition initiators. Specifically this invention relates to tactical devices used to initiate pyrotechnics and high explosives. More specifically, this invention relates to firing devices that permit the user to preselect a fixed time delay between arming and activation, allowing the user to escape the explosion area after arming the initiator.
Standard time delay firing devices used for initiating pyrotechnics and high explosives utilize a mechanical clock mechanism which releases a firing pin against a small charge (detonator) within the firing device. This detonator is located within an externally threaded snout designed to mate with a variety of booster devices.
The standard time delay firing device suffers from certain weaknesses rendering it unreliable and costly as a tactical weapon. Due to its mechanical nature, once fired in the field, it can not be reset and reused after initiating pyrotechnics without extensive refurbishing under laboratory or shop conditions. The detonator, located in the snout of a base coupling, blows forward to initiate the pyrotechnic device to which it is attached. In addition, it also blows backward into the timing device itself thereby damaging the timing mechanism. Repairs to this mechanical clock mechanism are prohibitively expensive. In addition, these mechanical time delay devices cannot be used to electrically fire remotely located demolition charges. They simply do not generate an electrical signal.
Furthermore, due to the gradual disappearance of clocksmiths and an industry-wide trend to the electronic measurement and display of time, the cost of building and maintaining mechanical mechanisms is increasing. In addition, mechanical devices are limited in the length of delay obtainable while maintaining high reliability of firing.
Another disadvantage of the mechanical devices in current use is their inability to be self-tested. The user must take them on blind faith in the field. There is no way to test the device to see if the timing mechanism is operative prior to use.